Shock absorber for aircraft



June 24, 1930. Q

L. w. GREVE SHOCK ABSORBER FOR AIRCRAFT Filed April 30, 1928 2 Sheets-Sheet l June 24, 1930.

L. W. GREVE SHOCK ABSORBER FOR AIRCRAFT Filed April 50. 1928 2 Sheets-Sheet 2 Jill! 11/ g am/11111 11111,

JPatJented June 24, I930 shock absorbers for air craft,

p of the shock absorber in direction,

UNITED STATES PATENT oFFrcE.

LOUIS w. serve, or cLnvnLANn, on1o, as'sionon TD, run onnvmnn rnnuma'rrc TOOL COMPANY, 'OI OLEV ELA ND,

OHIO, CORPORATION OF OHIO snocx ABSORBER r012. AIRCRAFT Applitation filed April 30,

' This invention ielates to improvements in I particularly amphibians. In air craft of this class the landing gear must be retracted at times when the plane is alighting upon the water. Otherwise the landing gear wouldjbe torn loose from the ship, because of the resistance ofi'ered by the relatively unyielding water through which the landing gear would have to pass rapidly. Consequently it is the general practice tomount the forward ground wheels u on movable frames or systemsof links an levers and to arrange for their operation usually from the pilots cockpit in order that the landing gear may be quickly and easily lowered into operative position or retracted whenever the occasion therefor arises.

This necessary movability of the landing gear and the relatively short pivotally mounted elements of the same which are employed to accomplish movability have rendered it difficult, if not impossible, to incorporate in the landing ear satisfactory shockabsorbing means of t ei types in use upon airplanes, and as a'result am hibians here-.. tofore have generally been without efiicient shock absorbing equipment, which obviously is detrimental tothe ratherdelicate structure of such craft and a source of discomfort to the pilot and passen ers. 7 One of theolnects o the present invention, therefore, is the provision of efiicient shock absorbing equipment for. the retractable landing gear of amphibians.

Another ob ect is the provision of a fluid shock absorber to be employedin the landing gear of an amphibian as a part, thereof which ordinarily occupies a substantially horizontal position, Y

Another object is the provision of a combined. li uid and air strut so designed and arrange that it will function properlyjand efficiently in a substantially horizontal posi tion. v

. Another objectvis'the provisionof an air dome extending laterally from the cylinder the cylinder'that in-none of the positions as of the. hull, with the the hull on each side 0 a generally vertical and so connected to'the interior of 1928; serial no. 278,929.

that embodiment of the invention which, for

the purposes of the present application, I

have illustrated in the accompanying drawin s, in which,

igure 1 is a transverse sectional view extending approximately half way through the hull of anam hibian and illustratlng a landing gear em odying my invention, said gear being in retracted position.

Figure 2 is a similar view of the other half corresponding portion of the landing gear shown in full lines in its operative position and in dotted lines in its 1no erative position.

igure 3 is a central longitudinal sectional view through the shock absorber strut with. the piston in extended position.

Figure 4 is a transverse sectional view taken substantiallyon the line 44 of Figure 3, and

Figures 5 and 6 are fra mental views illustrating the positions 0 assumed when the ly, respectively.

line of the hull of an amphibian plane is indicated by dotted lines, the lower surfaces at 10 and the curved up ersurface at 11,

the center being provided with a well 12 for the reception of a. portion of the wheel 13 of the landing gear when the latter is in it sretracted position. The surfaces 11 of the hull arenecessarily interrupted or cut into further for the accommodation of the bracing and retracting linkage presently to be described.

-The wheels 13 are-mounted for rotation upon axles 14 which are preferably bent substantially as shown in the drawings and attached at their inner ends by pivots 15 to the hull or its framework. A link 16 is also mounted upon the pivot 15 and at its other end is connectedby. a ivot 17 with one ex-' tremity of a'link 18, t e other extremity of the valve ring In Figures 1 and 2 of the drawings the outthe link 18 being pivotally attached to an ear 19 on the axle 14. The parts 14, 16 and 18 thus together constitute a triangular frame.

Mounted at fixed positions within the hull are a pair of ivots 21 upon which links 22 are mounted to swing. At the opposite ends these links carry pivots 23. Between the pivots 17 and 23 is mounted a shock absorber, which may, and preferably does. comprise a cylinder element 24 and a piston element 25.

In order to accomplish the movement of the landing gear from operative position to retracted position and vice versa, any suitabie means may be provided for swinging the link 22 upon the pivot 21. This is preferably accomplished, however, by providing the link 22 beyond the pivot 21 with a sec-. tor 26, the teeth of which mesh with a spiral gear 27, the two gears 27 being keyed upon a shaft 28 that may be rotated by any suit-- able means, not shown, such means being operable preferably from the pilots cockpit.

Referring now to Figures 3 and 4, wherein the detailed construction of the shock absorber is illustrated, it will be observed that the cylinder element 24 is provided upon its upper side near its closed end. with an integral annular upwardlyextending exteriorly threaded cup 29. This clip 29 has threadably mounted thereon a dome 30, the cup and dome together enclosin a chamber which is in communication wit the cylin-- der near the closed end thereof by means of open ports 31 and 32. The dome is provided with an oil filler opening closed by a threaded plug 33 and with an air valve 34 of any usual construction.

The cylinder element 24 at its open end is provided with an enlargement 35 for the reception of packing 36 which surrounds the skirt 37 of the piston element 25. Into the end of the enlargement 35 there isthreaded a packing gland nut 38. At'the opposite end of the gland there is a packing retainer ring 39, which normally rests against the shoulder 40 formed between the cylinder 24 and its enlargement 35. This ring 39 may move away from the shoulder 40 to some extent in response to pressure communicated to it from the space within the cylinder bewhat.

yond thepiston head 41 by way of'passages 42 and 43 throu h the piston head and ports 44 through a va ve ring 45. By this means the packing 36 may be automatically compressed moreor less to'make it tight when thepressure is heavy and to permit it to loosen uphwhen the pressure is relieved some is automatic regulation of the packing is disclosed more in detail in an application filed December 9, 1927 by John F. Wallace,'Serial No. 238,838.

The head of he cylinder. element 24 sgaf mounting lug '46 integraltherewith, arid a" pressure is reached. This similar lug 47 is provided at the outer end of piston element 25, these lugs being provided with openings for the reception of pivots 23 and 17 respectively.

When the landing gear is in operative position and the machine is making a landing or when it is taxiing over the ground,-

the cylinder and piston 24, 25 together'constitute a strut, in other Words, they erform the usual function of a shock a sorber. When the landing gear is being retracted, however, these two parts together constitute a tension element. At such times the head 41 of the piston presses through valve ring 45 against packing retainer ring 39, whereby the extension of the-parts is stopped or limited.

Each of the passages 42 has a restriction 42 therein. The ring 45 is loosely mounted so as to float in the s ace between the overhanging portion of t e piston head and theshoulder formed at the inner end of the iston skirt 37, the ports 44 in the ring being positioned to register'withithe passages 42 when the ring is in the osition illustrated in Figs. 3 and'6. When t e" ring 45 is in the position of Fig-- 5 the unrestricted passages 43 are open. When it is in the position of Fig. 6, however, these passages are closed.

The mounting of the shock absorber is, of course, such that the dome 30 extends above the cylinder 24. The plug 33 is removed and suflicient oil or otherili uidis poured into the filler hole to entireil hll the place within the cylinder-and exten up into the dome to about the level illustrated in Fig.3, when the piston is extended as far as it will go that is, when it is in the position illustrate in Fig. 3. Air is then pumped into the dome through the air valve 34 until the desired air is trapiped in the dome where it acts u on the sur ace of theliquid, and a consi erable amount of tilting of the shock absorber upon its mount-v ings may occur without permitting any air to get into the cylinder 24. It is relative? easy to maintain substantially oil ti sli ing surfaces between. the cylinder an piston,

but quite diliicult to make such joints tight against the esca of compressed air.'- I have so. positions the ports 31, 32, however, that when the'piston end of the shock absorber is "elevated, so that air'would tend to collect at the sliding surfaces, the oil above ports 31, 32 is relatively doe Consequently there is littleopportunity or air to escape from the dome' 2 30 and pass throu 11 ports 31, 32 intothe cylinder, eventhoug the oil washes about considerably due to shocks transmitted from the ground wheels."

0prati0rt.-Assuming tha the landing gear is in operative position, shown 'm ;Figure 2 and that .theplane is on the round,

the weight-of the plane is transmitte to the ground wheels through the shock absorbstrikes the ground with considerable force.

packing 36, 'whereb increased "friction as" ers, and consequently the pistons 41 are. ad-

tween the two telescoping members 24 and 25 when the plane is in the air.

When a landing is made the landing gear This force causes the piston head 41 in each strut to move rapidly inwardly in the cylinder 24, and this movement is transmitted by the oil into the dome 30, where it acts to compress the air therein. During this stroke the ring 45 is in the position of Figure 5, and a minimum resistance is offered to the flow of oil through passages 43 and 42 and through the ports 44 into the annular space 50 behind the piston head.

When the force of the impact is balanced.-

by the pressure built up in the dome 30, the

position when the ground wheel is in operative position, said 'nk'member includin a fluid'shock absorbing strut with a 'laterai lly extending fluid dome adapted to contain compresslble fluid.

2. In landing gear for amphibians, a

ground wheel, an axle therefor mounted to' swing upon the amphibian, a pair of bracing. members .connected together and to separated points of said axle to constitute a triangular frame, and a combined bracing and retracting means connected with the apex of said triangular frame said means comprising a fluid shock absorblng strut.

3. In' landing gear for amplnbians, a ground wheel, an axle therefor mounted to swing upon the amphibian, a plurality of 7 members connected with said axle forming a frame rigid in a plane transverse to the amphibian, and a combined bracing and retracting means pivotally connected with said frame at a point above the axle said means 'comprising a fluid shock absorbing strut.

In testimony whereof,l hereunto afiix my LOUIS w. GREVE.

signature.

piston stops and the energy thus stored up 1n the 'hi hly compressed air in the dome tendsto rive the iston outwardly with a violent motion. e piston head immediately catches up with the loose valve ring 45, as indicated in Figure 6, and the latter is held in this position by the pressure of Consequently the pasthe oil "behind it. sages 43 are closed and the oil from'the annular passa e 50 is permitted to flow out past the piston head only so fast as it can be metered throughthe restrictions 42' m the passages 42. The rebound is thus slowed up. t the same -time, however, the 10111 in the annular space 50-1sput'under ea mumcated to the retainer ring 39, moving the latter outwardly and compressingthe sists in slowing u t e rebound action.-

pressure, and this pressure is com- WhileI have i1 ustrated and described anv invention in considerable detail, such detail disclosure has been resorted to primarily for illustrative purposes, and is not to be construed as limiting the invention except as It may be included specifically in the appended claims.

Having thus described my invention what I claim is:

1. In landing gear for amphibians, a

- ground wheel, an axle therefor mounted to swing upon the amphibian, combined bracand retracting means connected wlth,

in sub axle'and with a fixed portion of the amphibian, said means comprisin a plurality of link members, one '0 said ink members occupying a substantially, horizontal 

